[OAI-implementers] SOAP-PMH

[Joachim Wackerow]

Just to clarify:
There is indeed an HTTP based approach of SOAP, it is called "The SOAP 
HTTP Binding". Here is an complete request example from the chapter 
"SOAP HTTP GET Usage" of the W3C SOAP Primer [1].

GET /travelcompany.example.org/reservations?code=FT35ZBQ  HTTP/1.1
Host: travelcompany.example.org
Accept: text/html;q=0.5, application/soap+xml

The answer is in an SOAP envelope, a specific client is needed (as with 
OAI-PMH?).

For example Fedora (Open-Source Digital Repository Management System) is 
using such an approach in the Fedora-API-A-LITE [2].


Regarding the question on advantages of SOAP see the interesting 
discussion threads two years ago on "OAI-PMH & SOAP":
http://www.openarchives.org/pipermail/oai-implementers/2002-January/000294.html
http://www.openarchives.org/pipermail/oai-implementers/2002-February/000305.html

A person of the Inktomi company is speaking for SOAP, see:
http://www.openarchives.org/pipermail/oai-implementers/2002-January/000296.html
http://www.openarchives.org/pipermail/oai-implementers/2002-February/000306.html
http://www.openarchives.org/pipermail/oai-implementers/2002-February/000309.html

I think some of his arguments are still important. Here are some 
snippets of his arguments:
"With a SOAP
interface, it would be fairly easy to build a harvester for
our search engine. It would be a very nice sample program for our
indexing interface. But with a one-of-a-kind XML protocol, it isn't
worth the trouble.

I believe that not using SOAP is a serious mistake. It means that
OAI will remain a niche protocol, with few implementations, few
users, and little positive effect.

With SOAP, you get scaling support, test suites, development tools,
supported libraries, directory service, etc. A custom protocol can
never catch up. And implementors have much better things to do
with their time than re-invent RPC."
"I want that library information to be easily available to all,
not just people willing to run a library-only protocol."
"With a SOAP protocol, any scripted web page can make a call to OAI.
Servers like DP9 and the repository explorer become very easy to
write. A professor's list of publications could be built from
the eprint data."
"OAI is already using an XML RPC. Switching from a non-standard XML
RPC to a standard one should be an obvious decision."



As fare as I know: Google is investing in SOAP [3] but not OAI-PMH.

Regards, Achim

References
[1] W3C SOAP Primer
http://www.w3.org/TR/2003/REC-soap12-part0-20030624/#L26854
[2] Fedora-API-A-LITE
http://www.fedora.info/definitions/1/0/api/#apialite
[3] Google Web APIs
http://www.google.com/apis/


Young,Jeff wrote:

 > It's not a question of SOAP vs. OAI, it's a question of SOAP vs. REST.
 > OAI could, in theory, operate using either transport mechanism.
 > Currently, the OAI protocol is based on the REST model, but some people
 > prefer the SOAP model (although I can't imagine why. ;-))
 >
 > In general, REST refers to the use of HTTP URL requests that produce
 > some form of HTTP response. This approach is so familiar to us with web
 > browsing that we don't even realize it is a convention for providing
 > lightweight web service like OAI and RSS.
 >
 > SOAP, OTOH, generally requires intelligent clients (compared to web
 > browsers) that can encode requests in SOAP wrappers and decode the SOAP
 > responses.
 >
 > Jeff